Laboratory balance



Jan. 15, 1952 l.. s. WILLIAMS LABORATORY BALANCE:

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7 Sheets-Sheet 5` Filed July 18, 1946 MM m 7 5. M @4M C n www 0 W Jan.,15, 1952 L. s. WILLIAMS 2,582,517

LABORATORY BALANCE Filed July 18, 1946 7 Sheets-Sheet 4 INVENTOR.

A TORNEYS Jan. 15, 1952 s. WILLIAMS 2,582,517

LABORATORY BALANCE 0W/ence J. /4//7//0/775 A TORNE YS Jan. l5, 1952 s.WILLIAMS LABORATORY BALANCE 7 Sheets-Sheet 7 Filed July 18, 1946Patented Jan. 15, 1952 LABORATORY BALANCE Lawrence S. Williams, Toledo,Ohio, assignor to Toledo Scale Company, Toledo, Ohio, a corporation ol'New Jersey Application July 18, 1946, Serial N o. 684,483

7 Claims.

This invention relates to weighing scales and in particular to weighingscales of the type designated generally as laboratory balances.

In laboratory work it is necessary that the technician be equipped witha weighing scale of extreme sensitivity so that various analyses can bemade with an extremely high degree of accuracy. The most common type oflaboratory balance is an even-armed hanging pan type of scale equippedwith relieving gears which lift the beam of the scale oil its bearingswhen a.; load or counterbalancing weights are being placed on either ofthe two pans. This type of scale, while extremely accurate also is veryslow because of the necessity for operating the relieving gear each timea weight is placed on or taken oi the Weight receiving pan. Thenecessity for snubbing the swinging pans of a laboratory balance of thistype further slows up the operation of such a balance.

It is the general object of this invention to provide a weighing scalevhaving a high enough degree of sensitivity to function as a laboratorybalance and yet be equipped with mechanism of the type employed incommercial scales so that A the speed of operation is made many times asfast as that of the conventional laboratory balance.

These objectives are achieved through the use of commercial scalecomponents which are rened in their design and construction so as tocontribute a minimum of error to the operation of the weighing scale. Inanalyzing the components of a weighing scale to determine how each couldbe bettered it was found necessary to isolate the error introduced byeach component into the total error of the scale and to so modify eachof these parts as to eliminate or greatly reduce these errors. Forexample, in conventional laboratory balances the weight receiving pansare hung below the weighing beam and are likely to oscillate in apendulum-like manner.

'In commercial scales on the other yhand the weight receiving plattersusually are mounted above the scale beam and are maintained in rstablecondition through the use of check links. It was found that conventionalcheck links introduce errors of large proportion and in the developmentof the instant laboratory balance I have invented check links whicheliminate all but a negligible small fraction of a grain of error causedby the check links themselves.

' Similarly, I have analyzed the design and construction of the bearingsand pivots, of counterforce structures, and motion damping devices,

and of the indicator mounting means and have so modified or redesignedconventional structuresvor invented novel structures that upon combiningthem I have constructed a scale having the advantage of high-speedoperation and providing accuracy comparable to that existing in the slowconventional style balances.

It is well known in the art that a projected indication aiords one ofthe simplest means of achieving wide indicator travel for smallincrements of weight. This very fact, however, while essential toaccuracy, results in it being diicult to gauge the approach to balanceor to estimate the degree of out-oi-balance existing at the start of'theweighing operation.

A primary object of this invention is to provide an indication whichwill permit a rapid determination of the correct number of largeincrements of weight required to counterbalance an unknown weight forexample, a still rapid but .more accurate determination of the nextsmaller increments of Weight and nally, an equally rapid but highlymagnified indication of the fractional portions of grains required toreach accurate balance.

In the drawings:

Figure I is a view in elevation of a laboratory balance embodying theinvention, its housing being shown in section and certain parts of thedevice being broken away and shown in section to more clearly illustratetheir operation.

Figure II is a plan view of the balance shown in Figure I with itsplatters removed.

Figure IH is a fragmentary elevational view on an enlarged scale of themain lever of the Weighing scale mechanism shown in Figures I and J1.

Figure IV is a vertical sectional view taken substantially on the lineIV-IV of Figure I.

Figure V is a plan view taken substantially from the position indicatedby the line V-V of Figure IV and shown on a slightly reduced scale.

Figure VI is a fragmentary sectional view takenk substantially from theposition indicated by the line VI-VI in Figure I and shown on anenlarged scale. A

Figure VII is a greatly enlarged fragmentary view in elevation of themain pivot and bearing and employed with the lever illustrated in FigureIII.

Figure VIII is a fragmentary vertical sectional View taken substantiallyon the line VIII- VIII of Figure VII.

Figure IX is an isometric view in detail and on an enlarged scale of thebearing means illustrated in Figures VII and VIII.

Figure X is an enlarged detail view, partly in elevation and withcertain parts broken away, taken substantially on the line X-X of FigureII.

Figure XI is a vertical sectional view taken substantially on the lineXI--XI of Figure X.

Figure XII is a fragmentary plan view of a variable poise.

Figure XIII is a detail view in section taken substantially on the lineXIII-XIII of Figure XII.

Figure XIV is a vertical sectional view taken substantially on the lineXIV- XIV of Figure X.

Figure XV is a fragmentary view in elevation of the indicator employedin the weighing scale illustrated in the figures and taken substantiallyfrom the position indicated by the line XV--XV of Figure I.

Figure XVI is a fragmentary vertical sectional view taken substantiallyfrom the position indicated by the line XVI- XVI of Figure XV.

Figure XVII is a fragmentary plan view on an enlarged scale of a mirrormounting bracket employed in the device illustrated in Figures I and II.

Figure XVIII is a fragmentary vertical sectional view takensubstantially on the line XVIII-XVIII of Figure XVII.

Figure XIX is a fragmentary vertical sectional view taken substantiallyon the line XIX--XIX of Figure XVII.

Figure XX is a fragmentary detail view partly in section of indicatordrive means and is taken substantially from the position shown in lineXX-XX of Figure XVI.

Figure XXI is a fragmentary plan view taken substantially from theposition indicated by the line XXI- XXI of Figure XV.

Figure XXII is a fragmentary vertical sectional view taken substantiallyon the line XXII-XXII of Figure XXI.

Figure XXIII is a detail view of pivot and bearing means employed withthe mechanism illustrated in Figure XXII.

Figure XXIV is a fragmentary view in elevation taken substantially fromthe position indicated by the line XXIV-XXIV of Figure XVI.

Figure XXV is a fragmentary view in elevation taken from the right ofFigure XXIV.

Figure XXVI is a View in elevation of the chart and indicating meansemployed in the weighing scale illustrated in the figures.

Figure XXVII is a vertical sectional View on an enlarged scale of motiondamping means employed in a weighing scale embodying the instantinvention.

Figure XXVIII is a fragmentary detailed view in elevation taken from theupper right hand side of Figure XXVII. v

A weighing scale embodying the instant invention may be erected on amain frame I which is substantially rectangular in plan view and servesto support the entire mechanism. The frame I is given rigidity byconstructing its Webs with substantial vertical dimensions and yetmaintained light by making the members relaitively thin. For example, inFigure I there is shown in cross section a cross web 2 of the frame I. Afulcrum stand 3 which is substantially U- shaped is fixed on the upperedges of the side members of the frame vI (see also Figure XI) and hastwo upwardly extending posts 4 which mount the fulcrum bearings of amain even-arm lever 5. The lever 5 has a pair of transversely extendingknife edge pivots 5 which are set into dove-tail slots 1 milled acrossthe under surfaces of the side frames of the main lever 5. The pivots 6each rest on the peripheries of a pair of ball bearings 8 (Figure IX)which are journaled by their balls on a horizontal pin shaft 9. Theshaft 9 extends through a horizontal bore I0 in a bearing block II. Thebearing block II has a downwardly turned V-edge I2 which rests in a V-groove I3 milled across the top of the post 4 of the fulcrum stand 3.The post 4 has a substantially rectangular cross section and avertically bored hole I4 of substantially circular cross section at itscenter. The V-groove I3 intersects the upper end of the circular hole I4and also intersects a rectangular milled slot I5 which extends acrossthe upper end of the post 4 at right angles to the V-groove I3. Thebearing block I I rests in the V-groove I3 and is retained thereinagainst longitudinal movement by a thrust plate I6 located at one endand a resilient clip I'I located at the other end, both the plate IS andclip I'I being secured to the post 4. The pin shaft 9 is retained in thebearing block II by a formed retaining clip I8 which resiliently graspscone-pointed ends of the shaft 9 and has a U- shaped body extendingdownwardly into the upper end of the hole I4.

Side thrust on the main lever 5 which would be transmitted through itspivots 6 is absorbed on each side by an adjustable thrust screw I9 whichis threaded horizontally through a resilient member 20 that is securedto the post'4 just beneath the transverse slot I5.

A load platter 2I (Figure I) is mounted on the upper end of a loadspider 22 which is pivotally supported on the left arms of the mainlever 5. A somewhat similar weight pan 23 is mounted on a weight spider24 which is pivotally supported on the right arms of the main lever 5.The spiders 22 and 24 are cup-shaped and have two arms 25 (Figure IV)which extend transversely across the main lever 5 to support the spideron the lever 5. At the end of each of the arms 25 there is located aninverted bored and slotted pivot post 26 which is constructedsubtstantially identically with the upper end of the fulcrum post 4 andwhich carries a bearing block 2'I in its inverted V-groove 28. A knifeedge pivot 29 is associated with each of the spider bearing blocks 21.The pivots 29 are mounted in transversely milled dove-tail slots cutthrough the upper surfaces of the arms of the main lever 5 with theirpivot edges lying on the same plane as the pivots 5; two of the pivots29 serving to support the load spider 22 and the other two of the pivots29 serving to support the weight spider 24.

In a Weighing scale having an extreme degree of accuracy it is necessaryto maintain the bearings and pivots with as nearly a perfect andunchangeable longitudinal distance between them as is possible. Inasmuchas the pivot distance, i. e. the distance from the pivot line of thefulcrum pivots 6 to the pivot lines of the knife edge pivots 29establishes the ratio of the Weighing scale lever 5 any slight change inthese distances will cause an inaccuracy in the operation of the scale.Since the pivots are fixed in their dovetail slots in the lever 5 thereis very little vpossibility that the distance between their knife edgeswill change except by deflection or temperature change in the length ofthe main lever 5. It is equally important that the distances between thesurfaces of the main bearings 8 and of similar load bearings 30 whichare supported by the bearing blocks 21 on which the pivots 29 rest bemaintained with equal accuracy. Because of the present construction, i.e. because the knife edges rest on the peripheries of cylindricalsurfaces any longitudinal change in position of these cylindricalbearing surfaces also results in a vertical change in position of thelines of contact between the pivots and their bearing surfaces. Thisalso will introduce error into the scale. To prevent any change in theposition of the bearings 8 and 36 with respect to each other and to holdthem spaced from each other the same distance as the edges of theirassociated pivots 6 and 29, there is provided a pair of stabilizingribbons 3|V one of which is associated with each group of three fpivots, i. e. pivot 29 of the load spider, 4main pivot 6 and pivot 29 ofthe weight spider.

Each of these stabilizing ribbons 3| is firmly secured at the outermostend oi' that left arm of the lever 5 along which it extends by means ofa retaining clip 32 (Figures II and III). The ribbon 3| is secured toeach of the bearing blocks 21 and to the bearing blocks with which it isassociated by being crimped and tightly forced into a slot 33 which iscut in a projection 34 formed on the lower flat surfaces of the bearingblocks v2`| and the upper ilat surface of the bearing block Tension isapplied and maintained on each of the ribbons 3| by a resilient U-shapedclip 35 which is secured to the end of the ribbon 3| by screws 36 andwhich is mounted in the end of the arm of the main lever 5 opposite tothat end of the lever 5 to which the ribbon 3| is attached. 'Ihe clip 35exerts constant tension on the ribbon 3| holding all of the bearingblocks tightly in position with the ribbon 3| taut.

The bearing blocks are equipped with two L-shaped retainer clips 31 asare each of the bearing blocks 21 for preventing the accidentaldisplacement in a vertical direction of the ribbons 3| and the bearingblocks. The bearing blocks 21 are equipped with thrust plates 38 andresilient retaining clips 39 which are similar to the plate and clips|6- and |1 and which are attached to the pivot posts 26 .of the spider.It is to be noted that the plates I6 and 38 are on the sides of thefulcrum post 4 and pivot posts 26 toward which the bearing blocks arepulled by the tension on the ribbons 3|. This maintains the bearingblocks 21 and the spiders which they support at fixed distances from thefulcrum posts 4 and since the ribbons 3| are attached to the lever 5 aswell, they hold the entire structure so far described in fixed relation-.f

ship. However, since the resilient retaining clips |1 and 39 are mountedon the opposite sides oi' the bearing blocks and since the resilientclip '35 would permit the ribbons 3| to be displaced la pair of thrustscrews 40 (Figure IV) which bear on the outermost ends of the pivots 29to absorb sidewise thrust on the spiders 22 and 24.

,Each of the thrust screws 40 is adjustably mounted in a resilientthrust absorbing member. 4|

which is secured to its pivot post 26 by a pair oi'v screws 42 and whichhas a stop screw 43 vin its loose end to stop its movement against the.arm of the lever 5 with which it is associated.

In order to insure that the spiders 22 and 24 v move vertically there isprovided a check link system which maintains a weighing parallelogram inthe manner usually employed in evenarm balances which have their weightand load receiving platters above their main lever. In scales of thistype the check link system is often a source of error since itintroduces friction infn the operation of the scale. In a scale asaccurate and sensitive as the present balance the amount of frictionintroduced by a conventional pin-mounted check link or even an improvedcheck link employing knife edge pivots and bear-v ings would destroy theaccuracy of the scale. The check link system employed in this balanceconsists of two tubular links 44 whichextend between a center check linkpost 45 (Figure XI) depending from the under side of the fulcrum stand 3and posts 46 (Figures IV and VI) which are adjustably mounted in thebottoms of cupshaped portions 41 of the spiders 22 and 24. Each oi' thetubular links 44 is flattened and horizontally drilled at its outer endthus forming an outer race 48 for a group of bearing balls 49. A smallplate 50 is spot welded on one side oi' the flattened portion of the endof the link 44 and a similar plate 5| is spot welded on the other sideof the flattened portion of the link 44. The plate 5| has a centrallylocated hole 52 which is concentric with the hole bored through theflattened end of the link 44. The plates 50 and 5| serve to retain theballs 49 within their race 48. A cone-pointed tenon 53 extends throughthe hole 52 into the check link where it is supported by the balls 49.The tenon 53 is formed on the end of an adjustable screw 54 which isthreaded horizontally through one oi' the arms 55 of a bifurcated stud56 extending downwardly from the check link post 46 of the spider 24. Acone-pointed thrust screw 51 is threaded through the other arm 58 of thebifurcated stud 56. The cone-points on the thrust screw 51 and the tenon53 bear on opposite sides of the plate 50. The construction of the outerend of the other one of the links 44 which is attached to the loadspider 22 is identical with the construction just described.

The stud 56 is vertically slidable within the post 46 and is preventedfrom turning therein by a pin 59 which extends transversely through thestud 56 and is engaged in a. slot 60 milled in the lower end of the post46. An adjustment screw 6| passes through a pair of spacers 62 bearingon the inner surface of the bottom of the cup portion 41 and is threadedinto the upper end of the bifurcated stud 56. A coil spring 63 surroundsthe stud 56 being located between the lower end of the post 46 and ashoulder 64 in the stud 56 just above its bifurcated portion. Rotationof the screw 6| draws the stud 56 up into the post 46 compressing thespring 63 permitting accurate. continuous, vertical adjustment. v

The centrally located ends of the links 44 are mounted between the threedownwardly extending arms oi' the central check link post 45 in a mannersimilar to that in which the outer ends of the links are mounted intheir studs 56. The central post 45 is threaded into a boss 65 (FigureXI) formed on the under side of the fulcrum stand 3 and has three arms66, 61, and 68 at its lowermost end. A pair of plates 69 and 18 arewelded one on each side of the flattened portions of each of the links44, the plates 10 having holes 1| which are concentric with larger holes12 horizontally bored through the flattened ends of the links 44.Bearing balls 13 which are located in the races thus formedsupport-cone-pointed tenons 14 of adjustable screws 15 whi-ch areoppositely directed and threaded through the two arms 66 and 68 towardeach other. The central arm 61 has a hole 16 concentric with theadjustable set screws 15 and the holes through which they are threaded.A pair of larger bearing balls 11 are located within the hole 16 andserve as inside thrust members for the two links 44, the surface of oneof the balls 11 and the cone-point of one of the tenons 14 pressing onopposite sides of each of the plates 69.

Thus, by adjustment of the screws 54 and l5 on whi-ch are formed thecone-pointed tenons 53 and 14 the check links 44 can be almostfrictionlessly maintained in position. Each of the check links 44 has aseries of holes 18 drilled through its upper wall with their centerlines falling on a plane lying at right angles to the center lines ofthetenons 53 and 14, i. e. the plane of movement of the check links 44. Bythus lessening the weight of the upper portion of the check links 44with respect to the lower portion thereof they are given a slight amountof pendularity whi-ch insures their hanging vertically on their supporttenons 53 and 14 and prevents tipping which would cause the check linksto bind against their thrust members (the various cone-pointed screwsand. the balls 11).

Since the vertical length of the central check link post 45 is xed andthe spider check link posts 46 are vertically adjustable, theparallelogram can be accurately set and maintained with the check links44 being kept substantially parallel to the arms of the main leverbeneath which they le. Vertical movement of the load spider 22 and loadplatter 2| and of the weight spider 24 and weight platter 23 and,consequently, the lever arm through which weights on the platters 2| and23 act, can be kept constant and identical, thereby insuring accuratebalancing. The vertical adjustment of the check link studs S6 which ismade possible by the construction above described alTords a simple andhighly accurate means of correcting so-called ratio errors. In theconstruction of a delicate balance it is almost impossible to socarefully machine the various parts that the lengths of the two arms ofthe main lever are identical or even extremely close to identical. theright arm of the lever as shown in Figure I were only a fraction of athousandth of an inch longer this length of the lever arm whenmultiplied by the load carried on the Weight spider 24 would create amoment the entire force of which would contribute error to the scale. Itis necessary, therefore, to provide some means for correcting this errorwhich can be adjusted to eiect the correction after the scale isassembled. The lengthening or shortening of the check link post 46 (i.e. moving the stud 56 vertically therein) distorts the weightparallelogram and as a result the weight spider 24 no longer remainsprecisely vertical but rotates slightly about the pivot axis as thelever oscillates. The moment of weights pla-ced on the weight platter 23changes in direction depending upon whether the post 46 has beenshortened or lengthened and in amount according to the distance oftheweights from a vertical plane through the knife edges. Thus, errorswhich occur because of a change or an original error in the ratio can becompensated for by the vertical adjustment of the check link post. Thismethod of adjusting for ratio errors, how- For example, if the length ofever, since it is a reversal of the usual reason for the use of checklinks in a scale of this type, requires that the weights which areplaced on the weight platter 23 be placed always a precise distance fromthe center line of the pivots 29 which support the weight spider and theplatter 23. If the weights were not always placed at the same distancefrom this pivot line but, instead, were placed either closer to thefulcrum pivot 6 or farther from the fulcrum pivot 6 their moment aboutthe fulcrum pivot would be changed very drastically since the adjustmentalready described tips the weight spider and its effective loading pointshifts about the center line of its r pivots instead of remainingdirectly thereon as it does when the weight spider is maintainedvertical. The weight receiving platter 23 (Figures IV and V) is mountedon the upper end of a pair of posts 19, which are studded into the armsof the spider 24, by means of two dowels which extend downwardly intobores 8| drilled in the upper ends of the posts 19. The dowels 80 areretained in the bores 8| by a pair of pointed set screws 82 which engagewith notches 83 cut in the dowels 8D. A hole 84 is drilled through theweight receiving platter 23 and is located generally above the head ofthe check link post adjusting screw 6| so that a screw driver can beinserted through the hole for adjusting the screw. A weight positioningfence 85 (Figure V) is iixed on the weight receiving platter 23 with the90 angle between its arms bisected by a vertical plane that is spacedfrom a vertical plane through the edges of the pivot 28. The fence 85 isdesigned for use with weights having a circular horizontal section andthus, regardless of the diameter of such weights, when they arepositioned against and between the arms of the fence 35 their centers ofgravity are correctly spaced from the center line of the pivots 29 andthus the elective lever arms of all the weights used are the samelength. This same result may be achieved in other ways, as for example,by the positioning of a short post on the weight platter and the use ofweights with vertical holes that t over the post. The load platter 2| ismounted on the upper end of the load spider 22 in a manner identicalwith that in which the vight platter 23 is mounted on the weight spiderThe main lever 5, while spoken of in general as a two-arm lever,actually is an open grill which has two side members and several Websconnecting the two side members. These webs are employed not only toform the frame of the lever but also one of the main webs 86 (Figures IIand III) carries a pair of balancing weights B1 and 88 which are usedfor balancing the lever 5 to permit the scale to be employed inout-oflevel condition and still to weigh accurately when in suchcondition. If the lever 5 were not balanced about the line of itsfulcrum pivots 6, and one end of the scale were lifted, the mass of thelever 5 would act as a pendulum and would require a certain amount ofthe weight on either the load platter 2| o1' weight platter 23 toovercome its pendularity and, therefore, identical weights on the twoplatters would not result in a balance. The weights 87 and 88 arethreaded on studs 89 and 90 respectively which extend horizontally anddownwardly from the web 86 of the lever 5. By adjusting the position ofthe two weights 81 and B8 on their respective studs the lever 5 can becompletely balanced so that the indication of balance will ancedcondition, a great deal of oscillation is likely to take place when theloads on the two platters are equal. This condition makes the reading ofany indication extremely diiiicult. This tendency of a weighing scale tooscillate when in balance is overcome in commercial weighing scales bythe use of some form of motion damping device. In the fine balance heredescribed a motion damping device is employed t limit the oscillationswhich take place but, since the balance is extremely sensitive thismotion damping device has also had to be studied and revised to removeas great an amount as possible of the friction `hherent in suchstructures. Figures XXVII and XXVIII illustrate the motion dampingdashpot employed in the present device. This motion damping dashpotconsists of a cup` 9| in which there is placed a quantity of a ne oil. Adiaphragm 92 is riveted on the lower end of a piston rod 93 which isthreaded and pinned into a bushing 94. The bushing 94 is grasped betweenthe bifurcations of a lower arm of a C-shaped bracket 95. An ear 96extends upwardly from the bushing 94 and is pierced with a horizontalhole 91 which forms a race for a group of bearing balls 98. Two plates99 and |00 are spot Welded on opposite sides of the ear 96, the plate|00 having a hole |9| which is concentric with the hole91 cut in the ear96. An elbow |02 is xed by a set screw |03 in an arm of the main lever 5extending horizontally therefrom and being turned downwardly at its endwhere it is riveted to the cross arm of a U-shaped yoke |04. Acone-point set screw |05 isvadjustably threaded through one arm of theyoke |04 and has a tenori |06 which extends through the hole |0| in theplate |00, being supported by the bearing balls 99 with its conepointagainst one side of the plate 99. Another cone-point screw |01 isthreaded through the other arm |04 with its cone-point lying on theopposite side of the plate 99 from the point on the screw |95 andconcentrically therewith.

At the upper end of the C-shaped bracket 95 there is located anadjustable weight |08 which is ring shaped and fitted on a short sleeve|09. The weight |08 is positioned on the sleeve |09 by a horizontal setscrew ||0. The sleeve |09 is secured to the bracket 95 and fixed inposition horizontally thereon by a screw which passes through a washerI2 overlying the upper end of the sleeve |09 and is threaded into thebracket 95. The body of the screw is of a diameter smaller than theinside diameter of the sleeve |09. Therefore, when the screw is loosenedthe'position of the sleeve |09 and the weight |08 mounted thereon can beshifted horizontally. Similarly, by loosening the screw ||0 the weight|08 canbe moved vertically. These two adjustments provide forcounterbalancing the weight of the diaphragm 92 and its connecting rod93 and balancing drag out of the connection formed by the balls 99 andtenoned screw |05` The ease with which the diaphragm 92 moves verticallyin the oil which is contained in the cup 9| depends upon how swiftly theoil is permitted to flow through a hole ||3 which is drilled in thediaphragm 92. This is controlled by a bimetallic baille |.4 whichoverlies the hole 10 H3. The baie ||4 is substantially U-shaped, one armof the U being secured to the upper surface of the diaphragm 92 and theother arm of the U continuing over and down to overlie the hole ||3 andhaving a hole ||5 through which the connecting rod 93 passes. The lowerAend of a sleeve ||6 presses against the upper surface of the upper armof the baie ||4 and is secured on a knurled thumb nut ||1 which isthreaded on the upper end of the connecting rod 93. The resiliency ofthe body of the baille ||4 tends to spread its two arms so that byvertically adjusting the thumb nut ||1 and the sleeve ||6 the distancebetween the arm of the batiie I|4 which overlies the hole ||3 and thediaphragm 92 can be adjusted to vary the ow of oil through the hole ||3.The baille ||4 is bimetallic in order that its arm will ex withtemperature changes and compensate for change in Viscosity of the oilvithin the cup 9|. A centrally pierced cap ||8 is threaded on the upperend of the cup 9| to exclude dust and other foreign matter.

The mechanism which has so far been described constitutes the loadreceiving and counterbalance Weight receiving structure of the scale andthe main lever of the scale on which these structures are supported andthat mechanism ancillary thereto for maintaining these members inaccurate balanceable condition. This mechanism alone is sufficient bothto support a'load being weighed and to counterbalance such load with adegree of accuracy hitherto unknown in scales of this semicommercialtype. However, in order to determine when a balance has been reachedindicating means are required capable of the same degree of accuracy asthe weighing means already described.

Indicating mechanism .that reason a direct mechanical indication whichis much less definitive than the projected indication also is employedin the instant invention.

The indicating mechanism is driven from an arm ||9 (Figure II) which isan extension on the right end of the main lever 5. At the end oi' thearm ||9 there is adjustably mounted a twoarm drive yoke |20 (Figures XXand XXI). The yoke |20 is vertically slidable on a pair of pins |2|which are studded into the end of the arm H9. The yoke |20 has a slot|22 in which the pins |2| slide and through which extends a set -screw|23 which is threaded into the end of the |30. The bearing |29 isengaged with a second y body las.

cone-pointed pivot |3| which is riveted in the horizontal cross arm of astirrup |32 (see also Figure XXII). A lower arm |33 of the yoke |20 hasa vertically adjustable retaining screw |34 threaded through its end andlocated coaxially with the pivot and with its upper end a suicientdistance below the stirrup |32 to prevent engagement therebetween but tolimit the movement of the parts with respect to each other and preventdisengagement of the cone-pointed pivots from their jeweled bearings.

The stirrup |32 is swivably mounted on a pair of horizontally extendingpins |35 (Figures XXI and XXII) secured in slots |36 on the faces ofbifurcations |31 of an indicator body |38. The indicator body |38 has apair of oppositely extending knife edge pivots |39 each of which restsin a V-slot |40- cut in a disk bearing |4| (Figure XXIII). The bearings|4| are each adjustably mounted in a collar |42 which contains a thrustplate |43 engaged with the end of the pivot |39, annular spacing rings|44 and a retaining ring |45 which is threaded into the collar |42 tohold the parts assembled therein. The collars |42 are mounted in a pairof bored ears |46 and |41 which are formed on an indicator stand |48erected on the end of the main frame The collars |42 are secured intheir respective ears |46 and |41 by retaining screws |49. A boss |50 isformed on the back of the indicator body |38 to balance the bifurcations|31 and a screw |5| is threaded into the end of the boss |50 so that byadjusting it in and out a nal balance can be reached.

One end of a loop counterforce spring |52 is secured by means of a screw|53 to the indicator The other end of the counterforce spring |52 isadjustable retained in a pair of clips |54 which are mounted on an arm|55 formed as an integral part of the ear |41. The retaining clips |54are vertically adjustable in a slot |56 milled in the surface of the arm|55 and are flared away from each other at their upper ends. One of theclips |54 has a substantially U-shaped cross section and the other clipis rectangular in cross section to fit between the arms of the U andclamp the loop counterforce spring |52 in the base of the U. The twoclips |54 are retained in the slot |56 by a plate |51 secured to the arm|55 by a pair of horizontally extending screws |58. The counterforcespring |52 is slidable vertically between the clips |54 and adjustabletherebetween so that its eiective counterforce can be adjusted to thedesired amount.

A socket |59 is brazed or welded on the upper portion of the indicatorbody |38 with its center line lying on the vertical plane of the edgesof the pivots |39. The socket |59 mounts an upwardly extending indicatorarm |60 at the uppermost end of which there is formed a flattenedpointer 6| (Figure XV). A similar socket |62 is brazed to the undersideof the indicator body |38 coaxially with the socket |59 and mounts adownwardly extending indicator arm |63. The pointer 6| sweeps along thearcuate edge of a chart |64 which is fixed on the uppermost end of anarm |65 in turn mounted on a bracket |66 which is adjustable securednear the upper end of a vertically extending post |61. The post |61 isstudded into a portion of the indicator stand |48. The chart |64 has aseries of over and under indicia |68 disposed along its lower arcuateedge. In Figure XXVI the series of indicia |68 is shown in solid linesand includes a plus sign and a minus sign; the plus sign being at theright i2 end of the series of the indicia |68 andthe minus sign at itsleft end.

It will be noted that the series of indicia |60 is divided into fortyminor divisions, twenty on v each side of the center line. The weighingscale embodying the instant invention is so adjusted that the indicatorarm |60 and its pointer |6| move from the center or balance position tothe outermost one of the indicia in the series |68 in response to achange in balance between the loads on the load receiving platter 2| andweight receiving platter 23 of twenty grains. Therefore, each of theminor divisions in the series of indicia |68 corresponds to a weight ofone grain when indicated by the pointer I6 Although the weighing scaleis a balance, i. e. it is designed so that a load being weighed is to becounterbalanced by weights deposited on the load receiving platter 23,slight degrees oi out-ofbalance, i. e. as much as twenty grains aredirectly indicated by the pointer |6| cooperating with its series ofindicia |68. This indication of as much as twenty grains over or underbalanced position results from the counterbalancing of this amount ofweight by the loop counterforce spring |52. It is necessary thereforefor the loop counterforce spring |52 to be delicately adjustable so thatits effective counterforce can be adjusted to accurately measure amountsof out-ofbalance of as much as twenty grains in either dircction in lineincrements.

There also is afforded in this balance an indica-- tion of finer degreesof out-of-balance in which the series of indicia |68 on the chart |64represent a total change of plus or minus two grains and each of theindividual indicia in the series |68 represents a change in balance ofone-tenth of one grain. This indication is provided by a projectionsystem. This projection system consists of a lamp |69 (Figure XVI) whichis mounted in a bracket |10 located between the side walls of the baseon a horizontal web |1| of the lmain frame l. Condensing lenses arelocated in a sleeve |12 which is secured to the underside of the web|1I. The lamp |69 and the condensing lenses in the sleeve |12 form aprojection path or beam of light which extends horizontally at rightangles to the plane of oscillation of the indicator arm |63.

A bracket |13 is iixed on the lowermost end of the indicator arm |63 andhas a downwardly extending pointer |14 at its lowermost end. The pointer|14 extends downwardly a suicient distance so that its arc of travelintersects the center line of the projection path of the condensorlenses |12 when the scale is at balance and the indicator arms |60 and|63 are vertical (as shown in Figure XV) A pair of projection lenses 15and |16 are mounted each in one of a pair of concentric sleeves |11 and|18 respectively. The sleeve |18 is threaded into a horizontal bore |19of a lens tube which is mounted in an ear |8| formed on the web |1|. Thesleeve |11 telescopes over the sleeve |18 and has a downwardly extendingear |82 in which is threaded an adjusting screw |83. A spring |84surrounds the screw |83 and presses against the ear |82 to hold thesleeve |11 at the limit of its adjustment, the screw |83 being locatedin the lower wall of the lens tube |80. A mirror |84 is fixed to the endof the lens tube |80 at the intersection of the center line of theprojection path of the lenses |15 and |16 and at a 45 degree anglethereto to reflect the image of the pointer |14 which is projected byprojection lenses upwardly and out of a vertical bore |85 in Athe lenstube |80. The light carrying the image of the pointer |14, after leavingthe mirror |84, travels upwardly until it hits the surface of a mirror|86 (Figures I and XV) which is mounted on Aan arm |81 of the bracket|66. The mirror |86 reects this beam of light .onto the chart |64wherethe image of the pointer |14 appears as shown by the broken shadowindicated by the numeral |14 in Figure XXVI.

The ratio between the lengths of the indicator .arms v|60 and |63including the pointers |6| and |14 and the optical ratio of theprojection sys- .tem described are such that the image of the pointer|14 moves ten times as far across the chart |64 with respect to theseries of indicia |68 as does the pointer |6| for the same increment ofweight. For example, if a weight of two grains were placed on the loadplatter 2| the indicator arm |60 would swing the pointer to that one ofthe indicium of the series of indicia |68 indicated by the letter a inFigure XXVI whereas the shadow of the pointer |14 would fall in linewith that indicium in the series of indicia |68 indicated by the letterA in Figure XXVI. The movement of the shadow of the pointer |14 acrossthe chart is caused by the movement of the pointer 14 to one side of theaxis of the projection path of the projection system.

'I'his movement of the shadow across the chart is extremely fast as canbe seen from the fact that a change in weight of only two grains causesit to move from zero to the extreme edge of the chart. In the meantime,however, the pointer |6| has moved only two of the individual incrementsof weight indicated by the indicia in the series |68. Thus the pointer|6| gives a gross indication of the degree of out-of-balance existing inthe scale and the projected shadow of the pointer |14 gives a neindication ofthe degree of out-of-balance of the scale. For example, ifit is desired to weigh out a predetermined quantity of a duid, weightstotaling the desired weight of the uid plus the weight of its containerare placed on the weight platter 23 and the empty container placed onthe load platter 2|. Liquid is then poured into the container rapidlyuntil the pointer |6| (which by virtue of excessive weight on the weightplatter 23 is at the far left side of the chart as shown in Figure XXVI)leaves the leftmost indicium in the series 68. The speed of pouring canthen be slowed down slightly but continued until the pointer |6|approaches the second indicium to the left from the center of the seriesof indicia. .|68. At this point the rate of pouring should besubstantially reduced and when the second 'indicium to the left isreached by the pointer :-'|.6| the shadow of the pointer |14 appears atthe left side of the chart |64. then poured with-a decreasing rate offlow as v-the shadow approaches the zero or center indicium until it isbrought exactly into balance by the additionof the last drop of liquid.

Similarly, if the weighing problem is not the "measuring of vapredetermined quantity but the T weighing of an unknown quantity, theloads can be -,placed on the platter 2| and weights ca n be placed onthe platter 23 in increments of at :least/:twenty grains at a time untilthe pointer |6| leaves the right side ofthe chart |64 where- .uponlesserincrements of weight can be added iuntil the shadow of -thepointer |14 appears at the; right side of the chart |64 and the remain-The liquid is 'sixteen ounces over erunder balance.

ing not-counterbalanced portion of the weight can be read directly fromthe chart.

Although the provision of these two cooperating indicating meansprovides not only a high degree of accuracy but also an opportunity todetermine the approach of the scale to a balanced condition. it also isdesirable to be able to estimate theweight of an4 unknown mass be' ingweighed so that weights of large increments of value, say ounces ormore, can first be used in an attempt to counterbalance the unknownweight and the weights of smaller value added only after a balancedcondition has been reasonably approached. For this reason there isprovided a gross weight estimator. 'Ihis mechanism makes use of theprojection system already described and of a separate counter forcemechanism which will counterbalance as much as This counterbalanceconsists of a spring leaf |88 (Figures II, XV et seq.). The leaf |88 issandwiched and welded at the end of a mounting bar |89 (Figure XXV whichis rockably mounted for adjustment in a vertical plane by a pair ofscrews |90 on a. semicylindrical rocker |9|. A right angle notch |92 ismilled across the bar |89 and a similar notch |93 is milled across araised center plateau |94 of the rocker |9|. A cylinder |95 is squeezedin the two notches |92 and |93 forming the bearing surface for theadjustment of the arm |89 with respect tothe rocker |9|. The rocker |9|rests in a notch |96 formed in the upper surface 0f a transverse web |91of the indicator stand |48. Two surfaces |98 are machined on 45 degreeangles to form the bearing -surfaces for the rocker |9|. The rocker isrotably adjustable on a horizontal axis in the notch |96 by a. pair ofscrews |99, each of which bears on a plate 200 resting with one of itsends on the upper surface of the web |91 and the other one of its endsbearing on the shoulder of the rocker |9|. Thus, by adjusting the screws|90 the leaf |88 can be swung angularly in a vertical plane and byadjusting vthe screws |99 it can be rotated on a horizontal axis atright angles to its angular movement.

The end of the leaf |88 extends between a pair of spaced bifurcations20| (Figures XX and XXII) which are formed on a. plate 202 mounted onthe end vof the arm ||9 along with the yoke |20 and held in placethereon by the pins |2I. The space between the bifurcations 20| is ofsuch size that the movement of the arm ||9 in response to out-of-balanceconditions of twenty grains or less is insufcient to engage the leaf |88with either of thel bifurcations and thus, there is no interference bythe leaf |88 with the counterbalancing action of the loop counterforce|52.

,The bracket |13 (Figure XV) has an adjustable screw 203 threadedthrough each of its outermost arms 264 on a center line which is radialwith respect to the pivot lines of the indicator pivots |39. Each of thescrews 203 has a pointer 205 at its lowermost end and is so adjusted inthe end of its arm 204 that the end of the pointer 205 lies onsubstantially the same arc as the pointer |14. The circumferentialdistances between the pointers 205 and the pointer |14 is such that thepointers 205 enter the projection path of the projection system of thescale when the leaf |88 engages the corresponding one of thebifurcations 20| and when the pointer |6| passes the last indicium atthe right or left of the series |68. A double series of indicia 206 isprinted on the chart 164 immediately above the series of indicia 188 andhas two ranges, a plus range from pero to sixteen ounces and a minusrange from zero to sixteen ounces. The pointers 285 and their screws203do not extend exactly the same distance into the projection path sinceit is necessary that the images of these pointers which are projected bythe projection system be thrown to a different place on the chart 288 tocooperate with their respective lines of indicia in the series 20G. Ascan be seen in Figure XXVI the shadow of the under pointer 285 followsalong Athe uppermost or under series of indicia. 288 while the overshadow follows in line with the over indicia in the series. In FigureXXVI both of the shadows of the pointers 205 are shown on the chart bythe broken lines indicated by the numerals 205, but in actual 0perationof the scale only one of these shadows would appear on the chart at atime.

For example, if it were desired to weigh an unknown quantity of acommodity the commodity would be placed on the platter 21. This wouldswing the pointer 16| to the right to the limit of the series of indicia168 and would introduce into the projection path the right hand one ofthe pointers 205, a shadow of which would be projected onto the chart|84 where it would fall somewhere along the series of indicia 206', letus say for example, in line with that indicium carrying the designation12. This would indicate that the weight of material is approximatelytwelve ounces and this amount of weight would be counterbalanced by theen- 1,;

gagement of the leaf |88 with the lower one of the bifurcations 201. Itwould then be pos sible to place upon the weight platter 23 eleven oneounce weights which would counterbalancc that much of the load and wouldcause the shadow of the pointer 205 to move to the left approaching thezero ounce indicium. A half ounce weight could then be placed on theweight platter and then a slightly smaller weight until finally asufficient amount of the load would be counterbalanced so that thepointer 181 would move away from the right sideof the series of indicia168. The remainder of the balancing procedure would be the same as thatalreadydescribed. j

By means of the adjustment afforded for the leaf 188 it can be tiltedand rocked to Vary the amount of lost motion between it and itscooperating bifurcations 20| to determine at what point the leaf wouldengage the bifurcations. This is a delicate adjustment inasmuch as theleaf must not engage the bifurcations until exactly twenty grainsut-of-balance condition exists and it must engage such bifurcations atexactly that time.

As was earlier explained with respect to the adjustable weights 81 and88 (see Figure III) the instant balance is designed so that it willweigh accurately when slightly out-of-level. The weights 81 and 88compensate for any pendularity which may exist in the main lever 5.Similarly, the indicator arm 160 carries a short sleeve 281 (see FiguresXV and XVI) which is slit near its ends and crimped slightly to grip theindicator arm firmly to hold it in whatever position it is placed tobalance the entire indicator unit comprising the indicator body 138, twoindicator arms |60 and 183 and the brackets mounted on the arms. Thus,with the main lever 5 balanced in one vertical plane and the indicatorShaft 216.

16 balanced in a vertical plane lying at right angles thereto the scalewill weigh accurately whether tilted sideways or fore and aft.

Tare mechanism In order to facilitate the use of the balance for theweighing out of predetermined quantities of material it is equipped witha continuously adjustable poise mechanism having a maximum capacity offive hundred grains and provided with a projected indication to enablethe amount of weight being counterbalanced by the poise to be directlyread. The poise mechanism has a hand wheel 208 (Figure I) which forms apart of a friction clutch 209 mounted in a bracket 210 secured to themain frame of the scale. The clutch 209 is fixed on the forward endof ashaft 211 the rear end of which is journaled in a pair of lugs 2|2extending outwardly from a poise frame 213 secured to the side of themain frame 1 at approximately its center. A worm 2|4 which is pinned onthe shaft 2|1 is in mesh with a worm gear 215 (Figure Xl) which in turnis secured on the outermost end of a. A drum 2|1 and a cam 218 also arefixed on the shaft 216. A pair of ribbons 219 are wound around andsecured to the periphery of the drum 2|1 and their free ends areattached to one end of a horizontally movable slide 220. The opposite(right hand- Figures X and XII) end of the slide 220 is secured to apoise 22|. The poise 221 is supported for travel along a U-shaped track222 by a pair o1.' flanged wheels 223 which are journaled on a pin 224extending transversely through the poise 221. The track 222 is supportedat one end on the main lever 5 by means of a bracket 225 (Figure XIV)which is riveted to one of the side webs of the lever 5. The track 222is adjustably secured to thebracket 225 by a bolt 226, the head of whichis riveted in the cross member' of the track 222 and a pair of adjustingscrews 221 which are threaded through the bracket 225 and bear on theunder surface of the track 222. The other end of the track 222 issupported on a bracket 228 which depends from the main lever 5 near itsmidpoint. A resiliently adjustable bolt 229 passes through a lug on thebracket 228 and is riveted to the bottom of the track 222. The bolt 229is raised or lowered to adjust the angular relationship between thetrack 222 and the main lever 5.

A third ribbon 230 is secured to and wound around the drum 2|1 at oneend and its opposite end is attached to the underside of an adjustable-slide 23| which is fitted in a bore 232 in the poise 221. A springtensioned adjusting screw 233 is threaded into the end of the slide 231and bears against the poise 221 to apply tension to Ithe ribbon 230.

Thus, when the hand crank 208 is rotated, through the worm 214 and wormgear 215, the shaft 2I6 and the drum 211 are rotated. This wraps orunwraps the ribbons 219 and 230 which moves the slide 229 and the poise22| longitudinally, the poise riding in the track 222 and beingsupported thereby on the lever 5. As the poise is moved farther awayfrom the main pivot andv bearing of the lever 5 it applies aprogressively greater moment to the lever and consequently willcounterbalance progressively greater loads placed on the load receivingplatter 21. It thus would be possible to place an empty container on theload platter and by turning the 'hand crank move the poise away from thecen- 17 ter of the lever until its weight exactly counterbalanced theweight of the container. This would put the scale in balance andeffectively tare-off the weight of the container.

It is desirable, however, to be able to read the amount of weight beingcounterbalanced by the poise. A separate projection system is providedfor accomplishing this. This projection system has a lamp 234 which isadjustably mounted in a lamp bracket 235 xed on an upper arm of thepoise frame 2 I3. A pair of condenser lenses which are located within alens cell 236 supported by the bracket 235 throws a beam of lightparallel to the center line of the main pivots of the lever 5.

A transparent indicia-bearing disk 231 is mounted on a ange 238 which issecured to the drum 2I1 by a plurality of cone-pointed set screws 239threaded through a rim of the drum 2I1 and into an annular V-groove 249cut in the hub of the flange 238. The transparent disk 231 carries acircularly arranged series of indicia ranging from zero to five hundredwhich rotate through the projection path of the condenser lenses 236 andare projected by a pair of projection lenses coaxially mounted therewithin a lens tube 24| which is fixed in a bracket 242 extending upwardlyfrom the poise frame 2 I3. By adjusting the set screws 239 in the groove240, the disk 231 can be adjusted to insure that the indicia bornethereby are properly concentric with their axis of rotation and inregister with the projection system. The ray of light carrying the imageof the indica on the transparent disk 231 passes through a cored hole243 in the side web of the lever 5 and strikes a mirror 244 which isadjustably mounted on an elbow 245 extending inwardly from the post 4 ofthe fulcrum stand 3. The mirror 244 reects the beam of lighthorizontally along the length of the lever 5 between its side webs andbetween the arms of the weight spider 24 until it strikes a secondmirror 246 (Figure I) which is adjustably mounted on the end of an arm241 located near the lower end of the post I 61. The mirror 246 reflectsthe beam of light upwardly where it strikes the mirror |86 and isreflected onto the chart I 64 to form a horizontally extending series ofindicia indicated by the numeral 248 in Figure XXVI. This series ofindicia is shown in broken lines in Figure XXVI because it is projectedonto the chart. An index. 249 (Figures XV and XXVI) is printed on thechart |64 in a position to lie adjacent the edge of the projectedindication 248 and to show the exact value in tenths of grains of theload being ,counterbalanced by the poise 22|. In this projectedindication the index is stationary and the projected indicia move acrossthe chart as the poise 22| is moved along the track 222.

Because of the long throw of the projection system and because of theconsequent rapidity with which the projected indication moves across thechart it is diiilcult to read this indication without slowing up themovement of the poise almost to a stop. Therefore, there is provided` apoise position estimator. An arm 250 (Figures X and XI) is supported bya leaf spring 25| from a depending arm 252 of the poise frame 2I3 and ispivoted on a pin 253 which is engaged in a slot 254 cut in the lowermostend of the arm 250. The pin 253 is riveted to an adjustably mountedbracket 255 secured to the arm 252. The upper end of the arm 252 is bentover horizontally to cross over the edge of the transparent disk 231 andcarries an index arm 256 which extends down behind the transparent disky231 and has an index 251 formed on its upper edge. The index 251 lies22| is at its most withdrawn position the cam 2 I8 is so located withrespect to the tab 258 of the arm 250 and is so mounted on the shaft 2I6that the index 251 is in position to be projected by the poiseprojection system onto the chart |64 in line with the zero indicium in aseries of indicia 259 printed on the chart |64. As the hand crank 268 isrotated and the poise 22| moved out on the track 222 the cam 2 I8rotates and through the tab 258 moves the arm 250 and index 251 to theright (Figure X) and a projected shadow of the index 251 to the right(Figure XXVI) across-` the chart |64 along the series of indicia 259. InFigure XXVI the projected indicia 248 are' so shown with respect totheir index 249 as to indicate that the poise is counterbalancing aweight; of 358.8 grains. Similarly, a projected shadow of the index 251(indicated by the numeral 251 in Figure XXVI) is positioned just shortof that indicium in the series 259 corresponding to a value f 360grains.

An arm 260 is formed on the drum 2 I 1, extending radially therefrom, toengage an adjustable stop screw 26| for positioning the drum at zerofBecause of the delicate adjustments necessary to properly focus thepoise projection system and to secure the proper angles of the mirrors244 and 246 so that the indicia and index'reflected thereby will becorrespondingly positioned on the chart I 64 there is provided anadjustable mounting means for the elbow 245 and for the mirrors 244 and246. (In Figures XVII, XVIII and XIX these adjusting means are shown indetail.) In general the adjusting means comprises a small diametercylinder resting in a groove cut in the one member, i. e. either thebracket or the adjusting member and clamped tightly therein by a screwor plate attached to the other member. One form of this mounting meansis illustrated in Figure XIX and is substantially similar to thatemployed in the mounting of the leaf |88 illustrated in Figures XIV andXV. The elbow 245 has a semicylindrical portion 262 through which is cuta semicircular groove and in which groove is mounted concentrically withthe body of the elbow 245 a small cylinder 263. A plate 264 is clampedagainst the periphery of the cylinder 263 by a pair of screws 265 andthe cylindrical outside surface of the body of the elbow 245 therebyclamped against the edges of a V-notch 266 out in the upper surface ofan arm on the frame 2I3 in which the elbow 245 is mounted. The bracketfor the mirror 244 has a vertical bore intoV which extends a set screw261 which bears on a small cylinder 268 located in a semicylindricalgroove 269 cut in a ilat 210 formed on the turned up end of the elbow245. The mirror 246 is mounted on its arm 241 in a manner almostidentical with the manner in which the mirror 244 is mounted on theelbow 245.

In a balance having the extreme sensitivity of the scale hereindescribed it is necessary to protect the mechanism from shock, preventthe ingress of any dust or particles of material weighed on the scaleand to protect it from drafts or currents of air which would deflect theparts.

The scale is mounted on a rigid base nZ'H. by reslientv mounting feet' 22', oneof' which is `secured tov the man-framel at each of its outercorners. Theeet 212 absorb' almost all external vibrations'or'shocksthliS protecting the delicate mechanisi. ToA prevent the ingress yofdust, the scale i's'eoipped with" a completely closed housing 213 whichishshaped to surround the entire weighing aliid'indicating mechanism andwhich has a window 5214* through which the chart |64 'is viewed. A'.secondary .housing` 2151"(Figure ID is formed around -thefadjustablepoise mechanism just desoribed. T Because dust, if allowed to accumulateon the load receiving platter 2| o1' weight platter 23, wouldtlfirowfthe laalancey out an appreciable amiin't, apair of dust covers216 are provided. 'Ihe covers Y216 can be leftover the platters 2|andf2f3'-when the egale isY not in use andV can be glaced ovefthematerial being weighed and the wfei'glitsor-the`weight platter in orderto eliminagtthe errors 'produced by'fd'rafts or air currents Strikingagainst veithefv "the material being weighedoftnefcoritegbaiancing'weights;' nffIlie embodiment' ofH the' 'inevntionwhich has beemdescribedfmay vbe modied to meetvarious ilgl-lil'm'ent."'W' A' A'Having'described the invention, I claim:

'in ,e laboratori' neiiinoe having reeiiieni means engaged near itslimits of travel vand serving tollimit movement of the balancemechanism, ilnoolnibineiione nivoielivlmoiinied indioeiioi'y en etonneoneri. nevinae' series of indioie for oooperation with said indicatorfor indicatinguceiqtain inorernenie Jof .voient .e nroieotion evsieniyinde);y on ysaid indicator, said index being moveine .in .ine nioieo ionnein of ,Seid projection System whereby an. image; of. Seid indei.i innfon s idreqhart to indicate lesserincree ts` of w ht Y'thanYthoserindiczritefd' by said tor, la*y p irofvpointe s mountedon saidin` r and movable alternatevly'` into said projec- A l e Y .iie1nnCe. inooniioinniion, n. niine'inniieiii 'even enn' d Ive?, eielndii bovineoreifnnd'iindeiii .g noie ininoie iiinn one orden of" .inofenienie enioineiio ooiinieifioiee ineenef oonneoied ioihe .leven on indionioi:driven looiinierioroe .inenne Seid ooiinieiioiee ioiniooiinieineienoineoeneoiiv OISPQQm U9 im? .I HLXEW?? V3.1?? of Said @Ver andunder".r'ijdicia,A in one ,order of increments, Seid indioeioi:beine.jdineoilrooonerenie'iviin Seid indioie' to 'indienne'vaines.ooiinieiiieieiieed by Seid ooiinieiioroe ineens.. ijn .Seidorder ofl inereis, ,en index! earned.. byleeid. indieion e vnio- V ionfsystemf 4forT arojeting a snadowoi lsaid index o to dchait forcoooejation with4 said indicia to indicate increments 'of' anotherorder, second automatic counterforce mans',`adiseng'a'geablfeconnectionbetween the Second countrfooe means and thelever that is engaged wh'erithe 'valuev` o the load ating theren'beComes greater than themaxir'num'fvalue counterbalanedbyfthefrst saidconlterorce means, d'indicatingnieans onsaid indicator for said secondcounter-force meansfsaid indicating means cooperating with ,indiciaonsaid chart in providin g indications of load. F

'Ina `,laboratorybalance, in lcombinatien, a snbeinn'iinliv even aimedleven e] 'onerifnevine 'inniiindei indieieieednbiein niioie ihnn oneOrder ncfemlmtsy cloumelffome mS-QQQT nected to the lever, an indicatord rven'bysaid counterforce means, said counterfor'ce means having atotal counterbalancing capacity corresponding tothe maximum Value ofsaid'oveij' and under indicia in one order of incrementshsaid indicatorbeing directly cooperable with said indicia to indicate Valuescounterbalanced by said counterforce means in said order of increments,an index carried by said indicator, a Aprojection system for projecting,a shadow of said,r index onto said chart for cooperation with saidindicia to indicate increments Mof anotherordr, asecondwcoimterforce"means, a disengageable Voon-v nection betweenthems'econd counterforce means and the lever that is engaged' when the:value ofthe load acting thereon becomesr'greater than the maximum valuecounterbalanced bythe first said counterforcefmeans, said charthaving aseries of indiciaV representing increments of load ccuntefrbalar'i'cedby lsaid Ysecond counterforce means', and a second index carried by saidindica-v ioi, Sdid'nioieoiion eve/#ein beine' edeniedlionroject a'shadoWof said secondindex onto said chart to dcooperate, with theseries ofindicia to indicati? the values of loads counterbalanced by said secondcounterfforc'e'means.

4. In a laboratory balance, inV combination, a enbeioniieiiv even.eiiined lever 'noneii nei/ine over andunder indicia readable in morethan one order of increments, counterforce means connected to thevlever, an indicator driven by said crounterforce means, saidcounteriorce e means having a total counterbalancing capacitycorresponding to the maximumvalue of said 'overand under indicia inoneoder of increments, Said indicator being directly cooperable withsaid in-V dicia,` to indicate values Countejjbalanced by saidcounterforce Ameans in said order oi increments, en indeX ooiried' .lov,Seid 'indioio'ion 'el'nroieotion system for projecting ashlafdowof saidindex onto said chart for 'coonerationrwith saidlindicia toA in dicateincrements of load` atgreater Inagnicaiion, e eeoondo'oiinieifoileeineene o dieeneoeeebie oonneoiion beineen ,ineSfeoondeoiinierforoe and a point of `the leverclosely adjacent the pointoioonneoiion beiweeifeeidlever. end ine nrsiseid counterfofrce mea s,said Adispengageaplo connection `being enrg'agedywhen the value of ,theload eoiine on ine lever neooinee `grenier than ine maximum valuecounter alanced bythe irstwsaid -unffoe l-@339s 3.1111 PdiCang -mfan$for said second counterforoe means.

5 In. e ienoitnioiy, b nionoe, in Voomloinetion o Subdinniieiivevlenernoed levend onori( having over and under indicia readable in more thanone order .ofinoienienie/ oonnierforee ineens oonneoied .io iiielievenen indioaior driven by sin eounienoiee. ineens, .said non ,enforceineens Hoving n ',ioini, .ooiinieinfiionoin'gloenaoiiv corresponcingi too the 'v maxirriuniA Yvalue of said over"and under indicia in "one orderincremeine Seid indieeior 'beine 4 diiefoiivv ooonerenle witli's/aidindioia'to indi'eate values counterbalanced Y'Joy saidcounlter'fo'rc'elmeans'in said order of increments, indexe" ,idibysaidfiidicton aprojection system Ffor projecting ma shadow` of said indefx 'ontosaidfohart for cooperationwwith said 'indiciaA` to indicate fireinents'nlof fanother order, a vsecond.'V couterforce means, a'disengageabl con'neotion",betweeri the` secondiconterfo'rc'e and apoint Qn tile' Y ieveif Aclosely -adjacent",the noiniof oonneeiionbetween `nini ,lever end ine iiidei@ ,ooiiiiierforoe Seid eonneotion@eine engaged `when inevelneof .the londaoting on the lever becomesgreater than the maximum value counterbalanced by the rst saidcounterforce means over and under indicia on said chart in the order ofincrements counterbalanced by said second counterforce means and a pairof pointers carried by said indicator and alternately positionable inthe projection path of said projection system for projection of a shadowof one o1' said pointers onto said chart for-cooperation with said lastmentioned indicia to indicate the increments counterbalanced by saidsecond counterforce means.

6. In a laboratory balance, in combination, a substantially even armedlever, a load receiver supported on one arm of said lever, a chart, aweight receiver supported on the other arm of said lever, an ,indicatorcooperating with the chart, counterforce means connecting said indicatorto said lever, said counterforce means being capable of counterbalancinga certain moment created by out-of-balance condition between the arms ofsaid lever, degree of out-of-balance indicia on said chart for directcooperation with said indicator to indicate the value of the momentcounterbalanced by said counterforce means, a variably positionableweight supported by and movable along said lever to change the degree ofout-of-balance between the arms of said lever and projection means forprojecting an indication of such change of out-of-balance condition ontosaid chart.

7. In a laboratory balance, in combination, a substantially even armedlever, a load receiver supported on one arm of said lever, a weightreceiver supported on the other arm of said lever, a chart, an indicatorcooperating with the chart,

a counterforce means connecting said indicator' to said lever, saidcounterforce means being capable of counterbalancing a certain momentcreated by out-of-balance condition between the arms of said lever,degree of out-of-balance indicia on said chart for direct cooperationwith said indicator to indicate the value of the moment counterbalancedby said counterforce means, a weight supported on said lever and movablealong the arm of said lever supporting said Weight receiver, manuallyoperable means for moving said weight, a transparent fine indiciabearing member movable by said manually operable means in proportion tothe movement of said weight, a projection system for projecting theindicia on said member onto said chart, an index lying in and movableacross the projection path of said projection system, and a series ofcoarse indicia on said chart for cooperation with the shadow of saidindex projected by said projection system.

LAWRENCE S. WILLIAMS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 842,688 Nilson Jan. 29, 19071,703,406 Schaper Feb. 26, 1929 1,856,704 Hadley May 3, 1932 2,300,282Eash Oct. 27, 1942 2,302,402 Sullivan Nov. 17, 1942 2,355,437 WeckerlyAug. 8, 1944 2,388,912 Haferl et al. Nov. 13, 1945

